The present invention relates very generally to the production of component parts that are pressurized during the production process such as, in the production of component parts that are formed by several component parts, which are to be joined together and glued together, or in the production of fiber composite components to compact the fiber composite work material and/or to bring the shape close to the final contour.
In particular, according to a first aspect, the present invention relates to a vacuum set-up to pressurize a component part while it is being produced, whereby the component part can, in particular, consist of at least one fiber composite component part and/or a component part that is to be glued on.
The vacuum set-up includes a base with a contact surface for the component part and an air-tight casing that can be sealed toward the contact surface (for example, plastic film) to cover the component part, to effect pressurizing the component part by evacuating the air trapped in the interior space of the casing.
A vacuum set-up of this type is known, for example, from German patent document DE 101 40 166 B4, in which it is used as infiltration and hardening tool in the production of a fiber composite component part. This vacuum set-up is used primarily for the infiltration of a semi-finished textile with a matrix material (e.g. resin system). Beyond that, in the subsequent thermal hardening of the infiltrated semi-finished fiber material, compacting or shaping that is close to the final contour can be achieved advantageously. An air-tight film is used as casing to cover the component part and it is sealed with a gasket that extends around the circumference of the component part to the contact surface of the infiltration and hardening tool. The known vacuum set-up is used to produce a 2-dimensional fiber composite component with relatively low component part thickness, so that the pressurization realized by evacuating the interior space of the casing essentially acts only orthogonally to the flat side of the component part upon the component part.
However, applications also exist in which a lateral pressure (i.e., parallel to the contact surface) acting on at least one edge of the component part is desired during the production of a component part.
This is the case, for example, when in a fiber composite component, a certain compacting in lateral direction and/or shaping in a lateral component part edge is to occur as well due to such pressure.
Lateral pressure is also advantageous then, for example, when one or several component parts forming a component part edge are to be connected with a “component part corpus” while the component part is being produced, and/or are to be firmly connected with each other. Such a connection can be provided, for example, as a “classic” conglutination, or also as a connection by what is referred to as “co-curing” or “co-bonding” in fiber composite technology.
For this, however, the vacuum set-up disclosed in DE 101 40 166 B4 is virtually unsuitable, because as a rule, the film used for pressurization does not mold 2-dimensionally or evenly onto the lateral component part edges. Lateral pressure exerted by the film on the component part edges is therefore often difficult to define or uneven, and cannot be limited for the desired final dimensions of the component parts.
Exemplary embodiments of the present invention provide a defined pressurization of the component part in lateral direction on at least one component part edge in a vacuum set-up of the type mentioned above.
In the vacuum set-up according to the invention, this problem is solved by a pressure strip system that can be mounted on at least one component part edge together with the component part in the interior space of the casing (e.g. film), that is formed by at least two pressure strips extending along the component part edge and over inclined planes working together in such a way, that pressure exerted by the evacuation of the interior space onto the pressure strip system causes the generation of pressure that is exerted laterally onto the component part edge.
The term “evacuation” is intended to describe any noteworthy lowering of pressure in the interior space of the casing of the vacuum set-up in a narrower sense. In general, however, any technique is to fall into this category, by which the pressure in the interior space is significantly lower than the pressure on the exterior side of the casing. In the event an especially large difference in pressure is desired between the interior space and the exterior space of the casing, this can be achieved by passing the vacuum set-up into a pressure vessel or a pressure tank, whereby the increase in exterior pressure that is caused by this, if needed, can also still be supported by applying heat.
By means of such a multi-part pressure strip system, an even and defined contact pressure can be achieved at the pertaining component part edge(s).
The pressure strip system functions, in a manner of speaking, as a “pressure redirection unit” for redirecting the “vertical pressure” (acting orthogonally to the contact surface on the pressure strip system) into a lateral direction (acting upon the component part parallel to the contact surface).
The lateral contact pressure generated according to the invention can be used, for example, for forming the pertaining component part edge(s) of the provided component parts—by pressing—during production of the component part at a component part corpus or on its edge, in order to achieve a particularly close connection between component part corpus and component part edge (e.g. by conglutination and/or fiber material compacting).
In particular, the lateral contact force can also be used for a well-defined “compression” of the pertaining component part edge. As will be evident in the following description of an exemplary embodiment of the invention, the pressure strip system can be designed in such a way that, according to the path, an exactly defined lateral compression of the component part forming the component part edge is achieved with the lateral pressure.
The vacuum set-up according to the invention can be used for nearly any shape of component parts and component part edges.
In particular, these can be fiber composite component parts in the broadest sense, i.e., component parts that are produced at least partially from a matrix material containing embedded reinforcement fibers. A specific application is gluing or laminating on a fiber material (single or multi-layered fiber material) that has been infiltrated with matrix material on at least one edge of the component part corpus, whereby the component part corpus itself can in turn consist of a fiber composite and/or other (e.g. metallic) components.
In accordance with one embodiment of the present invention, the vacuum set-up is used in the production of a 2-dimensional component part. This is to cover, in particular, component parts whose minimum lateral expansion at least doubles, in particular, is at least three times as large as their maximum expansion orthogonal to the contact surface (vertical direction).
For example, by using the invention, structural component parts and modules for vehicles, in particular aircraft can be produced very advantageously. A preferred use of the invention is, for example, the production of wings for aircraft, in particular, airfoils or parts thereof, for example, so-called “end edges” (e.g. aileron, rudder, pitch elevator or other flaps that are mounted displaceable at an aircraft wing or fuselage).
Many possibilities exist for the specific design of the pressure strip system.
According to one embodiment of the invention, the pressure strips work together via at least one inclined plane combination that extends inclined at an angle of 30° to 85° to the contact surface. Each combination of inclined planes can be formed by—abutting each other or sliding off each other—level inclined planes of adjacent pressure strips. The angle of inclination in such an inclined plane combination is determined by a “translation relationship” for the generation of the pressure acting laterally upon the component part edge depending on the pressure acting in vertical direction (orthogonal to the contact surface). Hereby, with a relatively large angle of inclination, for example, even a compressive force from a pressure strip acting on the component part edge in lateral direction on the component part edge can be generated that is larger than the pressure exerted in vertical direction by the pressure strip that works with it. According to one embodiment, the angle of inclination is at least 30°, in particular at least 40°. The laterally acting pressure becomes especially large when an angle of inclination of just under 90° is selected. However, it must be considered that in many applications an especially large lateral pressure (for example, larger than the vertical pressure) is not desired at all, so that often, an angle of inclination of at most 85°, in particular at the most 70° is preferred. Moreover, it must be considered that an angle of inclination that is selected to be especially large shortens that path, by which the pressure strip that is exerting the lateral pressure on the component part edge can be displaced in a vertical displacement of the of the pressure strip working with it toward the edge of the component part. In particular, when such a lateral displacement of the pressure strip exerting lateral pressure on the component part is desired (or is required for exerting a certain lateral pressure), the angle of inclination of the pertaining inclined planes should therefore not be selected all too large.
In one embodiment of the invention a pressure strip of the pressure strip system that is not directly adjacent to the component part edge is provided with a fixation unit for fastening this pressure strip to the contact surface. Accordingly, the pertaining pressure strip can be advantageously supported in lateral direction in such a way that it, when generating the pressure acting laterally upon the component part edge (by at least one additional pressure strip located between the component part edge and this fixated pressure strip) cannot “deviate away from the component part edge” in lateral direction. For this, it is sufficient when the fixation effected by the fixation unit prevents at least one motion of the pertaining pressure strip in the direction away from the component part edge.
Many possibilities exist for the configuration of the fixation unit. According to one embodiment of the invention, the fixation unit includes one or several horizontal bores, in particular bores extending orthogonally to the contact surface of the base (e.g. thread bores) in the pressure strip so that by inserting one or more fixing pins (or screwing in fixing screws), a fastening of the pertaining pressure strip on the contact surface can occur. Each such fixing pin or each such fixing screw then extends out of the bore of the pressure strip and further into a corresponding bore of the base, in order to effect a reliable anchoring of the pertaining pressure strip on the contact surface of the base. In one embodiment of the invention, the base is provided with a number of such corresponding fastening bores, so that the pertaining pressure strip can be fixated in various desired positions on the contact surface of the base depending on the application.
In one embodiment of the invention the fastening bores of the base respectively pass through this base completely, so that fastening pins or fastening screws can be inserted and/or screwed in from the underside of the base through the base and into the fastening bores of the pressure strip. In this embodiment, special sealing provisions are to be provided if necessary, in order to prevent air intake through the through bore-holes of the base into the evacuated interior space.
According to an alternative embodiment of the invention, which does not require such sealing measures, the fastening bores of the base do not completely pass through this base, i.e., they are formed as blind holes so that the fastening pins and/or fastening screws can extend from the upper side of the base into these blind holes of the base. In a more particular embodiment of the invention, the bores of the pressure strip are formed as through bore-holes, so that the fastening pins and/or fastening screws can be inserted and/or screwed in from the top, through the pressure strip, and further into the blind holes of the base.
In one embodiment of the invention the pressure strip system includes at least three adjacent pressure strips extending along the pertaining component part edge, of which the middle pressure strip works together with inclined plane combinations provided on both sides with the two outer pressure strips.
Preferably, angles of inclination, as already explained above, can be selected for both inclined plane combinations, whereby the two angles of inclination of the inclined plane combination provided on both sides of the middle pressure strip can be identical or can be selected to be different from each other.
That pressure strip which is located between the component part edge and the middle pressure strip can, for example, load this component part edge directly in lateral direction with its lateral surface that is facing the component part edge. Accordingly, an especially even distribution of the generated lateral pressure results, for example, when the pertaining lateral surface of this pressure strip is adapted to the shape of the component part edge. In the simplest case, this component part edge and correspondingly the lateral surface that is facing this component part edge of the pressure strip are level and extend, for example, orthogonal to the contact surface.
According to one embodiment of the invention, during the lateral pressurization of the component part edge, a more or less pronounced compression of the component part edge occurs by means of which the component part edge or the lateral component part edge surface is finally given the desired shape of the completed component part. For this purpose, the lateral surface of the pressure strip that is exerting the lateral pressure on the component part edge can be designed with the desired shape for the completed component part (for example, level or also curved, tiered, etc. depending on the desired final geometry of the component part edge). Thereby, subsequent processing of the component part edge can advantageously be simplified or even become entirely dispensable for achieving a desired final geometry.
As an alternative to a direct abutment of this outer pressure strip at the component part edge, at least one “adapter strip” in the vacuum set-up can be interposed between the pressure strip (exerting lateral pressure) and the component part edge, for example, in order to accomplish a shape adaptation of the surface that is exerting the lateral pressure to the form of the component part edge with such a strip.
The other one of the two outer pressure strips, i.e., that pressure strip which is located on the side of the middle pressure strip that is facing way from the component part edge, can be provided advantageously with a fixation unit of the type already described above, in order to prevent a motion of this pressure strip in the direction away from the component part edge. This pressure strip then functions so to speak as “support strip” that prevents a drawing back of the entire pressure strip system away from the component part.
As an alternative to a fixable pressure strip for support, instead of such a fixable pressure strip, a comparable industrial design of the contact surface of the base (“support shoulder”) or the contact surface with a fixed “support strip” at this position can be employed. However, this has the disadvantage that then the position of this support strip or support shoulder of the contact surface is fixed in advance. For this reason, a solution with a subsequently fixable support strip is better most of the time, in particular when the specific position of this support strip is to be variably selectable (for example, for producing component parts of various dimensions by using the same base or contact surface of the base).
The several pressure strips of the pressure strip system can, for example, be made of metal. In one embodiment, the pressure strip system consists of pressure strips extending straight, in particular, straight pressure strip profiles. This embodiment is particularly suited for the production of component parts with a correspondingly straight progression of the pertaining component part edge.
The pressure strip that lies anterior to the component part edge can have any shape corresponding to the desired component part edge in body contour and contour. In particular radii, for example, various angles, bezels and gradings are possible in the component part cross-section of the component part edge.
The pressure strip or “support strip” fixed on the base should, as a rule, be fixed running parallel to the component part edge. A middle pressure strip and/or a pressure strip extending directly adjacent to the component part edge can, for example, respectively be provided for the entire length with equal cross sections, for example, straight elongated profile strips.
According to a second aspect of the invention, a method is provided for producing a component part using a vacuum set-up of the type described above. The special embodiments and further developments already described above for the vacuum set-up can also be used in an analogous way for the production method according to the invention.
In one embodiment of the production method according to the invention, a pressure strip of the pressure strip system that is not directly adjacent to the component part edge is fixed onto the contact surface of the base before—by evacuating the interior space of the casing—pressurization of the component part and generation of lateral pressure on the component part edge is generated.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.